How to fix Error 4329 on Windows Server 2025 / Windows 11

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Why This Error Happens

Error 4329 occurs when SQL Server 2025 detects that the transaction log file you are attempting to restore contains log sequence number (LSN) records that predate the LSN mark already applied from a previous restore operation. This typically happens when log backups are applied out of sequence, when a log backup chain has a gap due to a missing intermediate file, or when the wrong backup file is selected during a point-in-time recovery. The database engine intentionally leaves the database in the RESTORING state to prevent data corruption until the correct, sequential log file is supplied.

Step-by-Step Resolution Guide

Step 1: Verify the Backup Chain Sequence

  • Query the msdb database to confirm the correct order of log backups using: SELECT backup_start_date, first_lsn, last_lsn, database_backup_lsn FROM msdb.dbo.backupset WHERE database_name = 'YourDB' ORDER BY backup_start_date;
  • Cross-reference the first_lsn and last_lsn values to identify any gaps or overlaps in the chain.
  • Confirm you are not attempting to reapply a log file that was already restored in a prior RESTORE LOG command.

Step 2: Identify the Correct Starting Point

  • Run RESTORE HEADERONLY FROM DISK = 'C:\Backups\YourDB_log.trn' to inspect the FirstLSN and LastLSN values embedded in the file header.
  • Compare this against the LSN currently applied to the database (visible via sys.database_recovery_status or the last successful restore output).
  • Discard any log backup file whose LastLSN is lower than the database’s current recovery LSN, as this is the root cause of the 4329 error.

Step 3: Restart the Restore Sequence from a Valid Full Backup

  • If the chain is broken beyond repair, restore a fresh Full Backup with WITH NORECOVERY to reset the baseline LSN.
  • Reapply subsequent Differential and Log backups in strict chronological order, ensuring each uses WITH NORECOVERY except the final file.
  • Store backup files in a clearly timestamped folder structure (e.g., C:\SQLBackups\YourDB\Logs\) to prevent future sequencing confusion on Windows Server 2025.

Step 4: Finalize the Recovery

  • Once the correct, sequential log file is identified and applied successfully, execute RESTORE DATABASE YourDB WITH RECOVERY to bring the database online.
  • Confirm there are no pending transactions required by checking the output message for “RESTORE DATABASE successfully processed.”

Alternative or Verification Steps

  • Verify the fix by running SELECT state_desc FROM sys.databases WHERE name = 'YourDB';—the status should return ONLINE rather than RESTORING.
  • If the correct log file is missing or corrupted, use SQL Server Management Studio’s (SSMS) Restore Database > Timeline visual tool to automatically detect and select the valid backup chain, bypassing manual LSN tracking entirely.